Farsightedness, medically known as hyperopia, is a common refractive error where distant objects are often seen clearly, but objects up close appear blurred. This occurs because the eye is either slightly too short or the cornea has too little curvature, causing incoming light to focus at a point behind the retina instead of directly on its surface. Contact lenses are a highly effective option for correcting hyperopia, offering a method that moves with the eye and provides a natural field of view.
How Contact Lenses Correct Hyperopia
The underlying optical principle for correcting farsightedness involves the use of a convex, or plus-powered, lens. This lens is designed to be thicker in the center and thinner toward the edges. When light rays pass through this convex surface, the lens bends and converges the light inward.
This converging effect brings the focal point forward, ensuring the light lands precisely on the retina. The contact lens compensates for the eye’s natural inability to focus soon enough by artificially increasing the eye’s focusing power. Because the lens sits directly on the eye’s surface, it becomes the first refractive element the light encounters, restoring clear vision for near and intermediate tasks.
Types of Contact Lenses Used for Farsightedness
Contact lenses for hyperopia are available in various formats, tailored to the wearer’s specific visual needs and age. Standard soft spherical lenses are a common choice, offering comfort and ease of use for many individuals with straightforward farsighted prescriptions. These lenses are generally made from hydrogel or silicone hydrogel materials, which allow oxygen to reach the cornea.
Rigid Gas Permeable (RGP) lenses are another option, often providing sharper vision for certain prescriptions because they hold their shape better than soft lenses. RGP lenses are durable and allow a substantial amount of oxygen to pass through the material. For patients over 40 who also experience presbyopia, specialized lenses become necessary.
Multifocal Lenses
Multifocal contact lenses address both distance and near vision simultaneously. These lenses incorporate multiple prescriptions across the surface, often arranged in concentric rings or an aspheric blend of powers. The brain learns to use the portion of the lens needed for the task, providing clear vision at various distances without the need for reading glasses.
Monovision
Another technique is monovision, where one eye is corrected for clear distance viewing, and the other eye is corrected for near viewing. The brain then integrates these two images to achieve functional clarity across different distances.
Choosing and Fitting Contact Lenses
The process of obtaining contact lenses for farsightedness begins with a comprehensive eye examination. The eye doctor first assesses overall eye health and measures the exact refractive error, which is expressed as a positive (+) power for hyperopia. Precise measurements of the eye’s physical dimensions are then performed to ensure an optimal fit.
Instruments like a keratometer are used to measure the curvature of the cornea, which determines the base curve of the lens. The eye doctor also evaluates the quality and quantity of the tear film, as this is important for lens comfort and overall eye health. Based on these measurements and a discussion of the patient’s lifestyle and visual demands, a specific lens type is recommended.
This consultation is important when considering multifocal or monovision options, as the choice depends on daily activities like driving or computer use. Trial lenses are then used to evaluate the fit, movement, and visual performance on the eye. Patients should expect a short adaptation period, especially when adjusting to multifocal or monovision lenses, to allow the brain to integrate the new visual input.